CN102754356B - System and method for frequency reuse within a cell in a relay network - Google Patents

Abstract

The present invention provides a method of communicating using a wireless communication network. The method may include: a Channel Quality Indicator (CQI) is received from a first UE. The first UE is served by a base station. The CQI characterizes a channel quality between the first UE and the base station when the base station transmits at high power. Based on the received CQI, a first Modulation and Coding Scheme (MCS) may be determined when the base station transmits at low power. The first UE may be communicated with using low power transmission when the spectral efficiency of the first MCS is equal to or higher than the spectral efficiency of a predetermined MCS. In some cases, a Physical Downlink Control Channel (PDCCH) Downlink Control Information (DCI) message is transmitted to the first UE to identify a Power Spectral Density (PSD) level.

Description

System and method for frequency reuse within a cell in a relay network

Cross References to Related Applications

This application claims U.S. Provisional Patent Application No. 61/303,919, filed February 12, 2010, entitled "SYSTEM ANDMETHOD FOR INTRA-CELL FREQUENCY REUSE IN A RELAY NETWORK" and filed February 12, 2010, entitled " Priority of U.S. Patent Application No. 12/704,739 for SYSTEM AND METHOD FOR INTRA-CELLFREQUENCY REUSE IN A RELAY NETWORK".

technical field

The present invention relates generally to data transmission in mobile communication systems, and more particularly to systems and methods for intra-cell frequency reuse in a communication network comprising one or more relay nodes.

Background technique

As used herein, the terms "user equipment" and "UE" may refer to wireless devices, such as mobile phones, personal digital assistants (PDAs), handheld or laptop computers, and similar devices with communication capabilities or other user Agent ("UA"). A UE may refer to a mobile or wireless device. The term "UE" may also refer to similarly capable but generally non-portable devices, such as desktop computers, set-top boxes, or network nodes.

In conventional wireless communication systems, transmission equipment in a base station transmits signals in a geographical area called a cell. As technology has evolved, more advanced equipment has been introduced that can provide services that were not possible in the past. This advanced equipment may include, for example, Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node Bs (eNBs) (rather than base stations), or other systems and devices that are more evolved than equivalent equipment in traditional wireless communication systems. Such advanced or next-generation equipment may be referred to herein as Long Term Evolution (LTE) equipment, and packet-based networks using such equipment may be referred to as Evolved Packet System (EPS). Additional improvements to LTE systems/devices will eventually lead to LTE-Advanced (LTE-A) systems. As used herein, the phrase "base station" or "access device" shall refer to any component that can provide a UE with access to other components in a communication system, such as a conventional base station or an LTE or LTE-A base station (including eNB ).

In a mobile communication system such as E-UTRAN, a base station provides radio access to one or more UEs. The base station includes a packet scheduler for dynamically scheduling downlink traffic data packet transmission and allocating uplink traffic data packet transmission resources for all UEs communicating with the base station. The functions of the scheduler include dividing the available air interface capacity among UEs, deciding the transport channel to be used for packet data transmission of each UE, and monitoring packet allocation and system load, among others. The scheduler dynamically allocates resources for physical downlink shared channel (PDSCH) and physical uplink shared channel (PUSCH) data transmission, and sends scheduling information to UEs through a scheduling channel on a physical downlink control channel (PDCCH). In some cases, control information is transmitted from the UE to the base station using a Physical Uplink Control Channel (PUCCH) or PUSCH.

Generally, communications between a base station and a UE are contained in one or more resource blocks (RBs). RBs provide a structure for encapsulating data within specific slots or symbols for transmission by a base station or UE at specific times. As known in the art, an example RB may include, for example, several resource elements (REs) arranged on frequency columns and time rows. In this case, each RE corresponds to a different time/frequency combination for transmitting data between the base station and the UE.

Hybrid Automatic Repeat Request (HARQ) is a scheme for retransmitting traffic data packets to compensate incorrectly received traffic packets transmitted between a base station and a UE. The HARQ scheme can be used in both uplink and downlink. Taking downlink transmissions as an example, for each downlink packet received by the UE, an acknowledgment (ACK) is sent from the UE to the base station on e.g. PUCCH after a cyclic redundancy check (CRC) performed by the UE indicates successful decoding ). If the CRC indicates that the packet was not correctly received, the UE HARQ entity sends a Negative Acknowledgment (NACK) eg on the PUCCH to request retransmission of the erroneously received packet. Once the HARQ NACK is sent to the base station, the UE waits to receive the retransmitted service data packets. When a retransmission request is received at the base station, the base station retransmits incorrectly received packets to the UE. This process of transmission, ACK/NACK, and retransmission continues until the packet is correctly received or the maximum number of retransmissions has been reached.

In some LTE radio access networks (RANs), relay nodes (RNs) can be incorporated into the network to improve cell edge performance and increase average cell throughput. For example, FIG. 1 is an illustration of an example network architecture including RNs located at the edge of a cell. As shown in FIG. 1 , network 100 includes base stations 102 and 104 . Base stations 102 and 104 communicate with Mobility Management Entity (MME)/Serving Gateway (SGW) 106 and 108, respectively, which provide core network functionality. In some cases, one or more UEs (e.g., UE 110) may communicate directly with either base stations 102 and 104 (concurrently or at different times). In other cases, however, when one or more UEs are unable to establish a strong connection with either base station 102 or 104, the UEs may instead communicate using one or more RNs 112, 114, 116 or 118. For example, as shown in FIG. 1, both UEs 120 and 122 communicate with the RN rather than directly with the base station. When communicating with the RN, data received by the RN from the UE is forwarded to the available base station for processing. Conversely, data allocated to a specific UE received by the RN from the base station is forwarded by the RN to the UE. Therefore, under this configuration, the UE can use the RN to access network resources with a higher data rate and/or lower power consumption.

Different types of RNs can be defined according to the functions of the RNs. Type IRNs are essentially small base stations with lower transmit power (eg, 30dBm) and in-band wireless backhaul. On the contrary, Type IIRN does not create a new cell, but only facilitates data transmission and reception for a specific base station. In general, a Type II relay does not have a separate physical cell ID and does not create any new network cells. Furthermore, Type II relays are transparent to Rel-8 UEs. Therefore, Rel-8 UE is unaware of the existence of Type IIRN. A Type II RN may transmit PDSCH, but not Cell Specific Reference Signal (CRS) or PDCCH. A UE in communication with a base station can use CRS to determine channel characteristics and allow the base station to schedule packet transmissions based on these channel characteristics. By comparing the received CRS with known reference signals (ie, known data), the UE can determine channel characteristics (eg, channel quality index, etc.). Differences between the known data and the received signal can indicate signal attenuation, path loss, interference levels, noise, and the like.

When implementing a network incorporating RNs, it is possible to provide more efficient coverage and/or higher efficiency if one or more of the base station and the associated RNs can simultaneously use the same resources to serve connected UEs. capacity. However, if the radio coverage of the RN and the base station overlap, it is difficult to reuse resources since the overlapping coverage can cause significant interference.

Description of drawings

For a more complete understanding of the present disclosure, reference is now made to the following brief description, taken in conjunction with the accompanying drawings and detailed description, wherein like reference numerals refer to like parts.

FIG. 1 is an illustration of an example LTE-A network architecture including a relay node (RN) located at a cell edge;

2 is an illustration of an example DL transmission scheme with intra-cell frequency reuse;

3 is an explanatory diagram of an example method for classifying cell-center UEs from cell-edge UEs in downlink (DL) communication;

4 is an explanatory diagram of an example configuration of resources of PUCCH format 1/1a/1b for transmitting uplink ACK/NACK in an existing network implementing LTE-8;

5 is an illustration of an example ACK/NACK resource configuration for minimizing collisions between ACK/NACK transmissions of UEs and RNs;

6 is an illustration of an example method of a transmission scheme for providing intra-cell frequency reuse in uplink (UL) communications;

Figure 7 is a graph showing the throughput gain of a Type II relay network with intra-cell frequency reuse, comparing CDF to user spectral efficiency;

Figure 8 is a diagram of a wireless communication system including a UE that may be used in some of the various embodiments of the present disclosure;

Figure 9 is a block diagram of a UE that may be used in some of the various embodiments of the present disclosure;

Figure 10 is a diagram of a software environment that can be implemented on a UE that can be used for some of the various embodiments of the present disclosure; and

Figure 11 is an illustrative general-purpose computer system suitable for some of the various embodiments of the present disclosure.

Detailed ways

The present invention relates generally to data transmission in mobile communication systems, and more particularly to systems and methods for intra-cell frequency reuse in a communication network including one or more relay nodes.

Some implementations include a method of communicating using a wireless communication network. The method includes receiving a channel quality indicator (CQI) from a first UE. The first UE is served by a base station. The CQI characterizes channel quality between the first UE and the base station when the base station transmits at high power. The method includes determining, based on the received CQI, a first modulation coding scheme (MCS) when the base station transmits at low power, and where the spectral efficiency of the first MCS is equal to or higher than that of a predetermined MCS , communicating with the first UE using low power transmission.

Other implementations include a method of communicating using a wireless communication network. The method includes receiving a first sounding reference signal (SRS) from a first UE, and receiving a second SRS forwarded from a relay node (RN). The second SRS is the first SRS observed by the RN. The method includes using the first SRS and the second SRS to determine a path loss between the first UE and the base station and a path loss between the first UE and the RN and sending the path loss difference to the first UE.

Other implementations include a method of communicating with at least one of a base station and a relay node (RN) using a wireless communication network. The method includes: sending a first sounding reference signal (SRS) to the base station, and receiving a path loss between a first user equipment (UE) and the base station and a path loss between the first UE and the RN The path loss difference between the path losses.

Other implementations include a base station for communicating using a wireless communication network. The base station includes a processor configured to receive a channel quality indicator (CQI) from a first UE. The first UE is served by the base station. The CQI characterizes channel quality between the first UE and the base station when the base station transmits at high power. The processor is configured to determine, based on the received CQI, a first modulation coding scheme (MCS) when the base station transmits at low power, and where a spectral efficiency of the first MCS is equal to or higher than a predetermined MCS When the spectral efficiency of , using low power transmission to communicate with the first UE.

Other implementations include a user equipment (UE) that communicates with at least one of a base station and a relay node (RN) using a wireless communication network. The UE includes: a processor configured to: send a first sounding reference signal (SRS) to the base station, and receive a path loss between the UE and the base station and a path loss between the UE and the RN The path loss difference between the path losses.

Other implementations include a method of communicating using a wireless communication network. The method includes broadcasting a first transmission to a UE. The UE is associated with a Relay Node (RN). The method includes at least one of receiving a first acknowledgment/negative acknowledgment (ACK/NACK) message from the UE, the first ACK/NACK being in an uplink control channel in response to the first transmission and receiving a second ACK/NACK message from the RN, the second ACK/NACK being sent within a second resource in an uplink control channel in response to the first transmission , the second resource is different from the first resource.

Other implementations include a communication system for communicating with user equipment (UE). The communication system includes a base station including a first processor configured to send a first message to the UE. The communication system includes a relay node (RN) in communication with the base station and the UE. The RN includes a second processor configured to receive the first message, and to send a data portion of the first message to the UE when the UE fails to decode the first message.

Other implementations include a base station that communicates using a wireless communication network. The base station includes a processor configured to: broadcast a first transmission to a UE. The UE is associated with a Relay Node (RN). The processor is configured to at least one of: receive a first acknowledgment/negative acknowledgment (ACK/NACK) message from the UE, the first ACK/NACK being an uplink response to the first transmission and receiving a second ACK/NACK message from the RN, the second ACK/NACK being a second ACK/NACK message in the uplink control channel in response to the first transmission The second resource is different from the first resource.

To the accomplishment of the foregoing and related ends, the invention comprises the features hereinafter fully described. The following description and drawings set forth in detail certain illustrative aspects of the invention. These aspects are indicative, however, of a few of the various ways in which the principles of the invention may be employed. Other aspects and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

Aspects of the invention are now described with reference to the drawings, wherein like reference numerals designate like or corresponding elements throughout. It should be understood, however, that the drawings and detailed description relating thereto are not intended to limit the claimed subject matter to the precise form disclosed. Rather, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the claimed subject matter.

As used herein, the terms "component," "system," and the like are intended to refer to a computer-related entity, which may be hardware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. As an illustration, both an application running on a computer and a computer can be a component. One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between two or more computers.

The term "example" is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as "example" is not necessarily to be construed as preferred or advantageous over other aspects or designs.

Furthermore, the disclosed subject matter can be implemented as a system, method, apparatus, or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof to control a computer or processor-based device to implement method described in detail in this paper. The term "article of manufacture" (or alternatively, "computer program product") as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier, or media. For example, computer-readable media may include (but are not limited to): magnetic storage devices (e.g., hard disk, floppy disk, magnetic strip...), optical disks (e.g., compact disc (CD), digital versatile disk (DVD). ..), smart cards, and flash memory devices (eg cards, sticks). Furthermore, it should be appreciated that a carrier wave can be employed to transport computer readable electronic data, such as data used in transmitting and receiving electronic mail, or in accessing a network such as the Internet or a local area network (LAN). Of course, those skilled in the art will recognize many modifications may be made to this configuration without departing from the scope or spirit of the claimed subject matter.

To significantly increase system capacity and coverage in Type II relay networks, the network can be configured for intra-cell frequency reuse. Typically RNs transmit at low power and cover a limited area. If there are multiple RNs in a cell that are separated from each other and have no coverage overlap, it is possible to schedule the multiple RNs to reuse the same resource blocks (RBs) while creating only negligible cross-interference. To further increase capacity, frequency reuse can be performed between multiple RNs and base stations. To minimize interference to UEs served by the RN, the base station may serve cell-center UEs with low-power data transmission, or disable resources occupied by the RN. In a typical Type II relay network, the PDCCH and CRS are transmitted from the base station. In this case, the UE served by the RN receives the PDCCH from the base station and the PDSCH from the base station and/or the RN. However, a UE served by a base station may receive both a PDCCH and a PDSCH from the base station.

In a particular network, each UE may be associated with a network node (eg, base station or RN) at which the UE observes the strongest downlink (DL) signal. In order to ensure that the UE is associated with the proper node (base station or RN), the base station may need access to information describing the radio conditions observed by the particular UE on the DL from the base station and/or by the RN on the UL on the wireless condition.

Since Type II RNs do not transmit CRSs which are originally used to estimate the channel strength between UE and network nodes, instead of CRSs, UEs can base their transmissions on uplink (UL) Sounding Reference Signals (SRS) or other UL signals received by RNs. transmission (eg, PUSCH transmission or random access preamble transmission) to be associated with a network node. To assist in network management, the RN may forward the received SRS signal strength averaged over a period of time to the base station. Accordingly, after receiving the report from the RN, the base station can determine the relative DL signal strength observed by the UE from the base station and available RNs. In response thereto, the base station may utilize the transmit power difference between the base station and the RN to adjust received SRS signal strength.

For example, assume that the received UL SRS strengths at the base station and RN are R0 and R1 respectively (note that in some cases, this value is averaged over a period of time), and assume that the DL transmit power from the base station and RN are P0 and P1 (typical values of P0 and P1 may be eg 46dBm and 30dBm). If R1>R0+P0-P1, the UE can be associated with the RN. If R1<=R0+P0-P1, the UE can associate with the base station. In some cases, a UE may be assigned to multiple RNs if it observes strong DL signals from multiple RNs. In this case, the base station signals to each RN the UE ID associated with the RN through high-layer signaling on the backhaul (eg, radio resource control (RRC) signaling or X2-based signaling). As the UE moves around, the RN can periodically forward the received SRS strength to the base station so that the base station can re-associate the UE with the proper RN. The base station may be configured to signal to the UE whether the UE is associated with the RN on the DL.

In one example, it is assumed that the UE is at the edge of the first cell 1 and very close to the RN in the neighboring cell 2 . If the RN observes a strong SRS from the UE (assuming the RN knows the UE's SRS configuration), the RN can report the received SRS strength to the base station of cell 2 . The base station in cell 2 may then forward the SRS report to the base station in cell 1 . Then the base station of cell 1 may decide to handover the UE to cell 2, and the UE may be associated with the RN. In this way, the UE may then become associated with the network node of the strong radio signal observed by the UE.

As described below, for a UE served by a base station, the base station may also classify the UE as a cell center UE (see, eg, UE 110 of FIG. 1 ) or a cell edge UE (see, eg, UE 124 of FIG. 1 ). If the UE is in the center of the cell, the UE can be co-scheduled with the UEs served by the RN, and each group of UEs shares the same RB. In this case, the base station transmits with a low power spectral density (PSD) to minimize interference to UEs served by the RN. If the UE is at the cell edge covered by the base station, the base station is required to transmit with a high PSD (causing interference to the RN). In this case, cell-edge UEs served by the base station cannot be co-scheduled with UEs served by the RN. In one example implementation, the base station is configured to transmit at 46 dBm and 30 dBm for the high and low power modes, respectively. In another embodiment, the low power mode may be 37dbm. In another embodiment, low power mode may refer to transmit power below 46dBm. The corresponding high and low PSD levels are 46dBm and 30dBm divided by the system bandwidth. In another scenario, the base station may disable resources allocated to UEs that are on the border of the RN's coverage but are still associated with the RN.

In one implementation, the base station informs UEs whether they are cell center UEs or not. This notification may be done on the DL via eg RRC signaling or Medium Access Control (MAC) control elements. Furthermore, for UEs served by the base station in the center of the cell, two transmission modes are possible (eg, high PSD transmission mode and low PSD transmission mode). In this case, the base station signals the mode information to the UE. As described below, the downlink control information (DCI) for cell center UEs may have 1 additional bit in the PDCCH to indicate whether the transmission mode is high PSD or low PSD. In some embodiments, the information may also be semi-statically signaled to the UE via higher layer signaling (eg, RRC signaling or MAC control element). In some other embodiments, the UE may use a predetermined algorithm or set of rules to derive this information.

2 is an illustration of an example DL transmission scheme with intra-cell frequency reuse. In step 150, the base station sends an initial transmission to the UE served by the RN in order to communicate with the UE served by the RN. Both UE and RN monitor PDCCH and decode packets. The UE will send ACK/NACK back to the base station.

In step 152, if the RN has successfully decoded the packet, but the UE has not successfully decoded the packet. In this example, on the subframes allocated for retransmission, the base station is the only network node sending the PDCCH, while the RN sends packet data. Therefore, the UE receives the PDCCH from the base station and the PDSCH from the RN. After the RN has successfully decoded the packet, the base station stops sending the PDSCH to the UE.

In step 154, using the same resource blocks that the RN uses to send packets to its UEs, the base station can transmit to the cell center UE with low PSD, and other RNs can also transmit to their UEs at the same time. Since there is no CRS from the RN, to facilitate data demodulation at the UE served by the RN, DRS may be assumed for transmission from the RN to the UE.

In order to minimize potential traffic bottlenecks on the backhaul link used by RNs for direct communication with base stations, advanced schemes such as space division multiple access (SDMA) can be employed so that base stations can communicate with multiple RNs simultaneously. Other advanced schemes on the backhaul could be multiple-input multiple-output (MIMO) transmission to increase link capacity from base station to RN.

A UE served by an RN may operate in several different configurations. Under the first configuration, the PDCCH is always scrambled using the UE's Cell Radio Network Temporary Identifier (C-RNTI). The PDCCH for the initial transmission is targeted to reach the RN and may or may not reach the UE. For example, if the RN is closer to the base station, a lower control channel element (CCE) aggregation level for PDCCH can be used to free up resources in the control region. After the RN decodes the packet, the PDCCH may be targeted to the UE (eg, using sufficient CCE aggregation level to reach the UE). Since the UE may not be able to receive the initial transmission due to lack of PDCCH, the base station can start the Hybrid Automatic Repeat Request (HARQ) redundancy version (starting from 0) at the 2nd transmission (or after the RN has decoded the packet) so that the UE can receive System information bits. Usually the systematic information bits in redundancy version 0 are important for packet decoding.

In the second mode of operating a UE served by an RN, it may be assumed that the PDCCH is always scrambled with the UE's C-RNTI and that the PDCCH is always targeted to reach the UE (eg, using sufficient CCE aggregation level to reach the UE). In this case, there is no need for the base station to restart the redundancy version on the 2nd retransmission (or after the RN has decoded the packet), since the UE should be able to receive the data signal on the initial transmission, although it may not be good enough Decode the data.

The PDCCH for initial transmission may be scrambled using the C-RNTI of the RN, and the PDCCH for retransmission may be scrambled using the C-RNTI of the UE. Since the UE will not receive the initial transmission, the base station can be configured to start the HARQ redundancy version (starting from 0) at the 2nd transmission (or after the RN has decoded the packet) so that the UE can receive system information bits.

In LTE Rel-8, adaptive asynchronous HARQ can be used on DL, which means that the base station dynamically schedules retransmission timing and retransmission modulation coding scheme (MCS) via PDCCH. RNs are typically half-duplex such that on a particular frequency, the RN is either receiving or transmitting at a given time. Therefore, it is difficult for the RN to monitor the PDCCH region during the first few OFDM symbols (e.g., 1 OFDM symbol) in one subframe due to the minimum switching time from reception to transmission mode and almost no time for the RN to decode the PDCCH, And perform retransmission according to the PDCCH in the remaining OFDM symbols. To minimize this difficulty, retransmission timing can be preconfigured. In this case, the base station still uses the PDCCH to notify the UE of the retransmission information (same as in Rel-8), but the resource allocation information and MCS information contained in the PDCCH signaling are the same as the initial transmission. Therefore, the RN does not need to read the PDCCH for retransmission. For the above-mentioned first mode of operation of the UE served by the RN, if the RN decodes the packet on initial transmission, the base station can use (0, 0, 2, 1, 3, 0, 2, 1, 3...) Sequence as a redundant version of HARQ.

Alternatively, the base station may send scheduling information (retransmitted subframe index, resource allocation, MCS, etc.) to the RN in advance. On the retransmission subframe, the base station can send the PDCCH, and the RN will send data. This implementation achieves the scheduling flexibility of adaptive asynchronous HARQ at the cost of additional signaling between the base station and RN. For Type II RNs that transmit CRS, PDCCH and PDSCH can be transmitted from the RN without the base station handling packet retransmissions.

For a UE served by the base station, the base station is configured to determine whether the UE is a cell center UE or a cell edge UE. The base station can co-schedule cell center UEs and UEs served by RNs on the same resource blocks via frequency reuse, but cannot do so for cell edge UEs served by the base station (where transmissions may interfere with one or more RNs). Therefore, the base station may be required to determine whether a particular UE served by the base station is a cell center UE or a cell edge UE. The same classification can also be applied to UEs associated with RNs. For RN-edge UEs associated with the RN, the base station may need to disable resources allocated to these UEs.

FIG. 3 is an explanatory diagram of an example method for classifying cell center UEs from cell edge UEs in DL communication. In this example, in step 160, the base station builds a mapping table between channel quality indicator (CQI) and signal to interference and noise ratio (SINR). In general, however, any channel indicator can be mapped to any value indicative of a signal level between one or more components of the wireless network. In this example, the SINR value in the mapping table is the SINR required to support various MCSs corresponding to a specific CQI. For an LTE/LTE-A system, the SINR value in the mapping table may be, for example, the lowest SINR supporting an MCS that achieves a 10% frame error rate (FER) after the first transmission. Alternatively, the SINR value in the mapping table may be an intermediate value of the SINR supporting the MCS achieving 10% FER after the first transmission.

In step 162, the UE estimates DL channel conditions based on the CRS and _pA . The UE can then report the CQI to the base station. ρ _A is a UE-specific parameter specified in Rel-8, indicating the ratio of PDSCH energy (EPRE) to CRS EPRE per resource element. The CQI corresponds to the CQI when the base station transmits with high power.

In step 164, the base station estimates the SINR of the base station-UE link according to the reported CQI through the CQI-to-SINR mapping table. Denote the SINR estimate as SINR ₁ .

In step 166, the SINR corresponding to the base station's low transmit PSD can be estimated as SINR ₂ =SINR ₁ *ρ _A,LP,max /ρ _A where ρ _A,LP,max is assumed to be in a low transmit power mode The ratio of PDSCH EPRE to CRS EPRE when the total base station power (eg 30dBm) is evenly distributed over the entire system bandwidth. In addition, an offset value Δ can be derived from SINR2 to account for interference transmitted from RN to UE. In some cases, the base station provides different values of _pA for the UE at high and low power, since the base station is aware of the UE's power level and can adjust _pA accordingly.

In step 168, using the mapping table established in step 160, the base station can map the time-averaged SINR ₂ (to remove the effect of fast fading) and find the highest supportable MCS. A user is classified as a cell center UE if the UE can support the lowest MCS level when the base station transmits at low power (eg, the lowest MCS level specified by Rel-8) or a specific predetermined or predefined MCS level. Otherwise, the UE may be classified as a cell edge UE. Alternatively, the base station may compare the spectral efficiency of the lowest MCS class with the spectral efficiency of a specific MCS class to determine whether the UE is a cell center UE and to determine the power level to use when communicating with the UE.

To enhance interference management and CQI estimation, a semi-static configuration of intra-frequency reuse can be coordinated between neighboring cells. Such a coordinated configuration can eg be transmitted between neighboring cells via the X2 interface. As an example, assume cell α has 2 neighbor cells β and γ. In this case, the system bandwidth can be divided into 3 parts: f1, f2 and f3. Cell α uses f1 for intra-cell frequency reuse, and the base station transmits with low PSD. Similarly, cells β and γ use f2 and f3 for intra-cell frequency reuse, respectively, and the base station transmits in low PSD mode. Alternatively, the available system bandwidth may be divided into 4 parts, wherein 3 frequency bands are configured as described above. In this case, a 4th part of the bandwidth can be used by the base station to transmit with high PSD or low PSD.

The network cells use a pre-defined configuration for the frequency reuse pattern, or, individually or in combination, the network cells may use distributed or centralized self-optimizing network (SON) techniques to converge to the reuse pattern. For example, each cell may send the area for the frequency band or the planning PSD for each RB to the neighbors of the cell. Then when the cell receives the planned PSD from the cell's neighbors, the cell can adjust the cell's PSD on the next transmission. Alternatively, the cell may send a planning PSD or indicator to enable the central coordinator to perform intra-cell frequency reuse. The central coordinator can then determine the proper reuse pattern to use and send the reuse pattern to the cells.

For the cell center UE, depending on whether the cell center UE is co-scheduled with the UE served by the RN, the base station can transmit on the PDSCH with high PSD or low PSD (note that no matter whether the transmission scheme is high PSD or low PSD on the PDSCH, always Send CRS on high PSD). The base station can use a low PSD if a cell center UE is co-scheduled with a UE served by an RN. However, if the cell center UE is not co-scheduled with UEs served by the RN, the base station can use low or high PSD. Switching between high and low PSD patterns on PDSCH can be done subframe by subframe.

In order for the UE to demodulate the received data, the UE needs to know the power ratio of PDSCH to CRS. Thus, analogous to the values ρ _A and ρ _B describing the ratio of PDSCH EPRE to CRS EPRE in OFDM symbols with and without CRS, respectively, when the base station is in high PSD mode, define 2 corresponding quantities ρ _A,LP and ρ _B,LP to indicate the ratio of PDSCH EPRE to CRSEPRE in OFDM symbols with and without CRS for low PSD mode.

The value of ρ _A,LP can be determined as follows. ρ _A,LP can be set to ρ _A,LP,max (as described above). Alternatively, ρ _A,LP is initially set to ρ _A,LP,max , then if necessary, ρ _A,LP is lowered according to an outer loop adjustment, e.g. if the FER of the highest MCS after the 1st transmission is less than a certain value (e.g. 10% or 1%), can reduce ρ _A,LP . After determining ρ _A,LP, ρ B,LP can be determined using ρ _B,LP =P _B *ρ _{A, LP} , where P _B is a Rel-8 cell-specific parameter configured by a high layer. The value of p _A,LP may then be communicated to the UE via eg RRC signaling. In some cases, instead of using ρ _A,LP and ρ _B,LP , different values of ρ _A,LP and ρ _B ,LP are provided by the base station for the UE at high and low power, since the base station knows the power level of the UE and can adjust ρ accordingly _A and _ρB . Updates to _pA and _pB may be signaled to the UE via higher layer signaling (eg, RRC signaling or a MAC control element).

In order to allow the cell center UE to know whether the packet transmission is in high PSD mode or in low PSD mode, a bit indicator may be added to the PDCCH DCI. In this case, the UE uses the proper power ratio of PDSCH to CRS for data demodulation. For example, when the power mode indicator is set to 1, the UE may be in high PSD mode. When the power mode indicator is set to 0, the UE may be in low PSD mode. A default value may be established such that the UE is in high PSD mode by default. In this case, whenever the power mode indicator is swapped from 0 to 1 or from 1 to 0, the UE may change from high PSD mode to low PSD mode.

After receiving the initial transmission from the base station, both the receiving UE and the RN may send an acknowledgment or negative acknowledgment (ACK/NACK) to the base station. Since UE and RN may send ACK/NACK at the same time, these 2 transmissions may destructively interfere with each other. Therefore, it is necessary to ensure that the ACK/NACK sent by the UE and the RN use different resources on the PUCCH to avoid collisions.

In LTE Rel-8, UE can generally use PUCCH resources Used to send HARQ ACK/NACK in subframe n. For the PDSCH transmission indicated by the detection of the corresponding PDCCH in subframe n-4, the UE may use Wherein, n _CCE is the number of the first CCE used to send the corresponding PDCCH DCI allocation, and Configured by higher layers. For the PDSCH transmission (for example, semi-persistent PDSCH transmission) that does not detect the corresponding PDCCH in subframe n-4, the UE can use Among them, it is determined according to the high-level configuration For example, FIG. 4 is an explanatory diagram of an example configuration of resources of PUCCH format 1/1a/1b for transmitting uplink ACK/NACK in an existing network implementing LTE-8. Unfortunately, there is a potential collision condition when ACK/NACK transmissions are sent simultaneously by UE and RN. Accordingly, the present systems and methods allow for offsetting or otherwise distinguishing ACK/NACK transmissions of UEs and RNs from each other to minimize collisions.

In one example, to avoid ACK/NACK collisions between transmissions from RN and UE, UE may be configured to use the same PUCCH resources as Rel-8, while RN sends ACK/NACK on PUCCH resources as follows. Allocate PUCCH resources to RN Used to send HARQ ACK/NACK in subframe n. For PDSCH transmission indicated by the detection of the corresponding PDCCH in subframe n-4, the RN may be configured to use Among them, it is configured by high-level signaling Can be set based on the maximum number of resources used for Values of : Persistent ACK/NACK, Scheduling Request (SR) and Dynamic ACK/NACK from UE, and Persistent ACK/NACK from RN. can be communicated to the RN via e.g. RRC signaling or System Information Block (SIB) or even pre-configuration value. For PDSCH transmissions for which no corresponding PDCCH is detected in subframe n-4, the RN can use in, Configured by higher layers. Can be set based on the maximum number of resources used for Values for: Persistent ACK/NACK, SR from UE, and Dynamic ACK/NACK. can be communicated to the RN via e.g. RRC signaling or SIB or even pre-configured value. FIG. 5 is an explanatory diagram of an example ACK/NACK resource configuration for minimizing collisions between ACK/NACK transmissions of UEs and RNs. As shown in Fig. 5, in the current scheme, resources available for UE ACK/NACK transmission are separated from resources allocated for RN ACK/NACK transmission. In addition to SRs for UEs, resources 202 are allocated for persistent ACK/NACKs and resources 204 are allocated for dynamic ACK/NACK responses from UEs. exist The resources 202 are allocated in , and the resources 202 are offset from the resources allocated for the RN. Referring again to FIG. 5, resources 206 are allocated for persistent ACK/NACK and SR to RN, and resources 208 are allocated for dynamic ACK/NACK responses. exist Allocate resources in 204, in Allocate resources 206 in. Therefore, ACK/NACK transmissions using persistent or dynamic resources are offset between UE and RN.

Alternatively, in order to minimize ACK/NACK collisions of UE and RN transmissions, RN may be configured not to send ACK/NACK transmissions. In this case, the base station is configured to assume that after the initial transmission, the RN can always decode the transmitted packets. If after the initial transmission, the UE does not decode the packet, the base station only sends the PDCCH on the retransmitted subframe, and expects that the RN may try to retransmit the data using the allocated resources. If neither the RN nor the UE decodes the packet at the initial transmission, the base station may retransmit the packet after the maximum number of retransmissions has been reached. In this implementation, the base station can be configured to use a conservative MCS to ensure that the RN can successfully receive and decode packets with a very high probability of initial transmission.

Alternatively, the base station may use the RN-ID instead of the UE-ID to send group grant information on the PDCCH dedicated to RN. In this case the UE will not detect any grant on the PDCCH and will not send any ACK/NACK in response. In this case, there will not be any ACK/NACK resource conflicts.

Alternatively, a dedicated channel may also be allocated to the RN to return ACK/NACK information to the base station to ensure that it does not conflict with the ACK/NACK information sent by the UE. The dedicated channel may be a physical channel to explicitly or implicitly associate ACK/NACK to DL transmissions, eg, through a pre-configured timing relationship. The RN may alternatively transmit the ACK/NACK information to the base station through a MAC control element or high-layer signaling. Information such as the index of the transport block (TB) or the lowest PRB index of the PDSCH can be included in the signaling so that the base station can correctly associate the HARQ feedback with the DL transmission.

In existing Type II relay networks, CRS can only be sent by the base station, and no CRS transmission is broadcast from the RN. When the RN sends data to the UE, the RN is generally configured to blank resource elements of the CRS. Therefore, when a UE served by a base station estimates CQI from the CRS, the UE takes into account interference from adjacent base stations and inter-cell RNs, but does not consider interference from intra-cell RNs. Since the RN interference in the cell is not measured, the interference cannot be compensated, resulting in the inability to perform accurate link adaptation.

In the present system, for a cell center UE served by a base station using a low PSD transmission mode, as described above, the UE may be configured to derive the CQI of the low PSD mode based on the CQI of the high PSD mode. Therefore, the estimated CQI of the low PSD mode does not consider the interference from RNs in the cell.

In the case of a UE served by an RN, the base station may derive the CQI of the RN-UE link based on the CQI of the base station-UE link. In this case, the base station can estimate the RN- SINR of the UE link. Therefore, the estimation of the CQI of the RN-UE link may not consider the base station/RN interference in the cell.

To alleviate these estimation problems, outer loops can be applied to further tune the MCS. For example, for each cell center UE served by the base station, the base station may collect long-term average FER statistics and HARQ termination statistics for packets transmitted in low and high PSD modes, respectively. Similarly, for each UE served by the RN and cell-edge UE served by the base station, the base station may collect long-term average FER statistics and HARQ termination statistics. The long-term average can then be a window-based moving average. Assuming that the goal of MCS selection is x% FER after N transmissions, if the actually observed average FER after N transmissions is higher than x%, then the base station can use a lower MCS. Otherwise a higher MCS should be used. This adjustment is achieved by directly adjusting the MCS (MCS plus/minus a delta value), or by adjusting the estimated SINR for mapping to the MCS (SINR plus/minus a delta value). After outer-loop MCS adjustment, if a cell-center UE served by a base station cannot support the lowest MCS in low-PSD mode (e.g., the lowest MCS level specified in Rel-8), the UE can be classified as a cell-edge UE . Similarly, after MCS adjustment, if the UE served by the RN cannot support the lowest MCS, the UE can switch to being served by the base station. Alternatively, the base station may compare the spectral efficiency of the lowest MCS level with the spectral efficiency of a specific MCS level to determine whether the UE is a cell edge UE and to determine the power level to use when communicating with the UE.

Alternatively, improved CQI estimation can be obtained by estimating intra-cell interference. In this case, the RN may report the received UE PUSCH power to the base station. The base station can then estimate the path loss from the RN to the UE via eg Power Headroom (PHR). If the base station knows the RN transmission power, the base station can estimate the interference power from the RN to the UE. Similarly, the base station can use the PHR to know the path loss from the base station to the UE and estimate the interference from the base station to the UE served by the RN. Therefore, the base station can determine an improved MCS estimate considering the intra-cell interference from the base station and RN.

In case of UE UL communication, each UE can be assigned to a base station or RN. The allocation may be based on the path loss experienced between the UE and the base station and between the UE and the RN. This path loss may be derived from uplink SRS transmissions or other uplink transmissions such as PUSCH transmissions and random access preamble transmissions. The RN may forward the received SRS signal strength averaged over a period of time to the base station for analysis. If the base station observes a stronger SRS, the UE can associate with the base station. Otherwise the UE can associate with the RN. The UE may alternatively be assigned to multiple RNs if they see strong SRS from the UE. The base station may signal the allocated UE ID to each RN on the UL using eg RRC signaling. After processing the path loss measurements, the base station may signal the UE to indicate whether the UE is associated with the RN or the base station on the UL.

For a UE served by a base station, the UE may be classified as one of a cell center UE or a cell edge UE. For UL, the same procedure as described for DL above can be used to determine whether a UE is a cell center or a cell edge. However, in the case of UL, assuming that the transmit power of the base station is the same as that of the RN, ρ _A,LP,max can be equal to the power ratio of PDSCH to CRS. If the UE is in the cell center, the UE can be co-scheduled on the same resource block as the UE served by the RN, since the cell center UE is configured to transmit with a low PSD, thereby causing minimal interference to the UE served by the RN. However, if the UE is at the cell edge, the UE cannot be co-scheduled with UEs served by the RN because the cell edge UEs will transmit with high PSD and thus can interfere with the UEs served by the RN. The base station may use, for example, RRC signaling to inform the UE whether it is a UE served by the base station at the center of the cell or a UE at the edge of the cell on UL.

6 is an illustration of an example method of a transmission scheme for providing intra-cell frequency reuse in UL communications. In step 180, the UE served by the RN has uplink data to send to the RN. In this case, SR is indicated to the base station. In step 182, the base station notifies the UE of the scheduling grant via PDCCH DCI format 0. The RN also detects the PDCCH using the blind decoding procedure as described for Rel-8 UEs. So after step 182 the RN knows when, where and how to receive the UL initial transmission from the UE.

In step 184, the UE performs an initial UL transmission. Both the base station and the RN receive the UL transmission. In one implementation, the base station is configured to send ACK/NACK in response to a UL transmission from the UE, while the RN is not configured to send such ACK/NACK. In this case, the UE may be configured to always assume successful reception and decoding of UL packets by the RN after the initial transmission. Both UE and RN then listen for ACK/NACK from the base station. If the base station does not decode the UL packet after the initial transmission, then on subframes for retransmission, the UE does not attempt to retransmit the UL packet and instead assumes that the RN will retransmit the transmission. In this implementation, the base station can schedule a conservative MCS to ensure that the RN will have a very high probability of receiving and decoding the packet on initial transmission. If neither the RN nor the base station successfully decodes the packet during the initial transmission, the UE may retransmit the packet after reaching the maximum number of retransmissions.

Alternatively, the base station may be configured to send ACK/NACK, and the RN may be configured to quickly indicate to the base station the state of the RN's uplink reception. Both UE and RN can then monitor the ACK/NACK from the base station. If the base station does not successfully receive and decode the packet, but the RN successfully receives and decodes the packet, the RN may attempt to initiate a subsequent retransmission of the packet. However, if neither the RN nor the base station successfully receives the packet, the base station can apply adaptive uplink HARQ transmission and request the UE to retransmit the packet again. In some cases, dedicated signaling may be established to communicate packet reception status at the RN to the base station.

Using the same resource blocks that the UE originally used to transmit the UE's uplink packets to the UE's RN, the cell center UE can transmit directly to the base station, and other UEs served by the RN can also transmit to their RN at the same time.

In a manner similar to DL communication, intra-frequency reuse can be coordinated between neighboring cells for improved interference management and channel condition estimation. In one example, there are 3 neighbor cells and the system bandwidth is divided into 3 parts: fl, f2 and f3. Cell 1 uses f1 and f2 for intra-cell frequency reuse, cell 2 uses f1 and f3 for intra-cell frequency reuse, and cell 3 uses f2 and f3 for intra-cell frequency reuse. Such an intra-frequency reuse coordinated configuration can be transmitted between neighboring cells via eg the X2 interface. Alternatively, the available system bandwidth can be divided into 4 parts, where the 4th region is used without any restriction of any cell. The width of the fourth region can be adjusted according to changes in the load and amount of resources required for frequency reuse in the cell.

When realizing frequency reuse in a cell using this system, the target of UE sending PSD of PUCCH can be the base station, so as to ensure that the base station receives the control information at an appropriate time. Generally speaking, if the UE is served by the base station, the target of the transmitted PSD of the SRS and PUSCH may be the base station, or if the UE is served by the RN, the target of the transmitted PSD of the SRS and PUSCH may be the RN.

For RN-served UEs, the SRS may be targeted to the serving RN to ensure that other network nodes in the system (eg, base stations and RNs) can receive accurate assessments of UL channel conditions and interference levels. In order to minimize interference to other UEs, the PUSCH transmit power of UEs served by the RN is generally configured to target the RN.

In order for the UE to set the SRS/PUSCH power to the proper level to reach the RN, the UE needs to know the RN-UE path loss. For determining the RN-UE path loss, when the UE wakes up from idle mode for the first time, the UE may not know whether the UE is associated with the base station or the RN. In this case, the UE sets the transmission PSD of the base station-targeted SRS using the estimated base station-UE path loss. The RN may also receive the SRS and forward the received or observed SRS strength to the base station. If for UL communication the UE is to be served by the RN (i.e. the RN sees a stronger SRS), the base station determines the base-UE link and RN- Path loss difference between UE links. In some cases, the base station informs the UE of the path loss difference via RRC signaling, and the UE uses this information to determine the RN-UE path loss. Afterwards, the UE can set the SRS/PUSCH power at an appropriate level to communicate with the RN. During the active period, the RN may continue to forward received SRS strengths to the base station. In this case, the base station monitors the SRS strength at the base station and RN. If the UE moves out of the RN coverage area and becomes served by the base station, the base station notifies the UE so that the UE can set the PSD of SRS and PUSCH based on the base station-UE path loss to effectively communicate with the base station. Since the SRS targets the RN for UEs served by the RN, the RN has access to an estimate of the UL channel condition. Therefore, the RN may be required to forward the estimated MCS and the power control command to the base station, so that the base station may send the estimated MCS and the power control command to the UE in the PDCCH.

In the case of intra-cell frequency reuse, the UL channel condition estimated from the SRS may not include intra-cell interference. In this way, a similar outer loop adjustment as described above can be achieved to perform MCS compensation. Accordingly, for each UE, the base station collects long-term average FER statistics and HARQ termination statistics. Assuming that the target of MCS selection is x% FER after N transmissions, if the actually observed average FER after N transmissions is higher than x%, then the base station can use a lower MCS. Otherwise, a higher MCS can be used. This adjustment can be achieved by adjusting the MCS directly or by adjusting the estimated SINR for mapping to a specific MCS. After outer loop MCS adjustment, if the cell center UE served by the base station cannot support the lowest MCS (e.g., the lowest MCS level specified in Rel-8), the UE may be classified as a cell edge UE and may be instructed not to communicate with the cell center UE served by the base station The UEs served by the RN reuse frequencies. Similarly, after MCS adjustment, if one or more UEs served by the RN cannot support the minimum MCS, these UEs served by the RN may switch to being served by the base station. Alternatively, the base station may compare the spectral efficiency of the lowest MCS level with the spectral efficiency of a specific MCS level to determine whether the UE is a cell center UE and to determine the power level to use when communicating with the UE.

According to the simulation parameters in Table 1, the simulation of this system is carried out

Table 1

In this simulation, a network with 57 sectors with a site-to-site distance of 0.5 km was used. Each sector has 4 RNs evenly placed at a distance of 4/5 cell radius from the eNB. There are 25 users per sector distributed in a hot zone fashion. For each of the 4 RNs, there are 5 users within 30m around the RN to ensure that these 5 UEs are in the coverage of the RN (i.e., the UE sees a higher signal strength from the RN than from the eNB) . The remaining 5 UEs are macro UEs, which evenly fall within the sector. Adopt the channel model in R1-093726 "Text proposal for channel model and evaluation methodology", CMCC, #58. Directional receive antennas at the RN are assumed to improve backhaul link quality.

In the simulation, a proportional fair (PF) scheduler with full bandwidth allocation is employed. As described in R1-094461, "DL performance evaluation of Type-II relay", RIM, #59, in the case of using full bandwidth resource allocation, allocating resource blocks of the entire subframe to one user relieves the Scheduling constraints brought about by half-duplex nodes. It is assumed that the eNB can transmit to multiple RNs simultaneously on the backhaul using an advanced transmission scheme such as SDMA. In one subframe, if one or more RNs transmit to UEs served by the RNs, the eNB may schedule cell center UEs using the transmit power of the PDSCH reduced to 30dBm. Intra-cell frequency reuse is not used for the subframes sent by the eNB to the cell edge UE.

Since there is no CRS from the relay node, the eNB cannot explicitly know the link quality of the RN-UE link. In the simulation, as in R1-094461, "DL performance evaluation of Type-II relay", RIM, #59, the eNB uses the large-scale path loss difference between the eNB-UE and RN-UE links and the The eNB-UE SINR is scaled by the transmit power difference between the RN and the RN to estimate the RN-UE link quality. It is also assumed that the RN monitors the CRS from the eNB and the feedback CQI of the backhaul link. The MCS of the UE served by the RN is selected as the smaller of the MCSs that can be supported by the backhaul and the RN-UE link.

In conjunction with Table 2, FIG. 7 is an explanatory diagram showing the throughput gain of a Type II relay network with intra-cell frequency reuse. For 4 RNs per sector and hot zone UE distribution, a gain of 70.9% is observed in cell throughput and a gain of 67.9% in cell edge throughput is observed compared to traditional eNB network.

Table 2

FIG. 8 shows a wireless communication system including an embodiment of UE 10. UE 10 is used to implement aspects of the present disclosure, but the present disclosure should not be limited to these implementations. Although illustrated as a mobile phone, UE 10 may take various forms, including wireless handsets, pagers, personal digital assistants (PDAs), portable computers, tablet computers, laptop computers. Many suitable devices combine some or all of these functions. In some embodiments of the present disclosure, UE 10 is not a general-purpose computing device like a portable, laptop, or tablet computer, but a dedicated communication device, such as a mobile phone, wireless handset, pager, PDA, or communication device installed in a vehicle . The UE 10 may also be, include, or be included in a similarly capable but non-portable device, such as a desktop computer, a set-top box, or a network node. UE 10 can support special activities such as gaming, inventory control, job control and/or task management functions and more.

UE 10 includes display 702. The UE 10 also includes a touch-sensitive surface, a keypad, or other input keys collectively referred to as 704 for user input. The keyboard may be a full or reduced alphanumeric keyboard (such as QWERTY, Dvorak, AZERTY, and sequential types) or a traditional numeric keypad with letters associated with a telephone keypad. Input keys may include a scroll wheel, an escape or leave key, a trackball, and other navigation or function keys that may be pressed inward to provide other input functions. UE 10 may present options for the user to select, controls for the user to actuate, and/or cursors or other indicators for the user to direct.

The UE 10 may also accept data input from the user, including dialed numbers or various parameter values for configuring the operation of the UE 10. In response to user commands, UE 10 may also execute one or more software or firmware applications. These applications can configure the UE 10 to perform various customized functions in response to user interaction. Furthermore, the UE 10 may be programmed and/or configured over the air from, for example, a wireless base station, a wireless access point, or a peer UE 10.

Among the various applications executable by UE 10 is a web browser, enabling display 702 to present web pages. The web page may be obtained via wireless communication with a wireless network access node, cell tower, peer UE 10, or any other wireless communication network or system 700. Network 700 is connected to a wired network 708, such as the Internet. Via wireless links and wired networks, UE 10 has access to information on various servers, such as server 710. Server 710 may provide content that may be shown on display 702 . Alternatively, the UE 10 may access the network 700 through a peer UE 10 acting as an intermediate device, with a relay type or hop type connection.

FIG. 9 shows a block diagram of UE 10. Although various known components of the UE 110 are shown, in an embodiment, the UE 10 may include a subset of the listed components and/or additional components not listed. UE 10 includes a digital signal processor (DSP) 802 and memory 804. As shown, UE 10 may also include antenna and front-end unit 806, radio frequency (RF) transceiver 808, analog baseband processing unit 810, microphone 812, earpiece 814, headset port 816, input/output interface 818, removable memory Card 820, Universal Serial Bus (USB) port 822, short-range wireless communication subsystem 824, alarm 826, keypad 828, liquid crystal display (LCD) (may include touch-sensitive surface 830, LCD controller 832), charge coupled device (CCD) camera 834 , camera controller 836 and global positioning system (GPS) sensor 838 . In an embodiment, the UE 10 may include another display that does not provide a touch-sensitive screen. In an embodiment, DSP 802 may communicate directly with memory 804 without going through input/output interface 818.

DSP 802 or some other form of controller or central processing unit controls the various components of UE 10 according to embedded software or firmware stored in memory 804 or in memory contained in DSP 802 itself. In addition to embedded software or firmware, DSP 802 may execute other applications stored in memory 804 or available via an information carrier medium such as a portable data storage medium such as a removable memory card 820 or via wired or wireless network communication other applications. The application software may include a compiled set of machine-readable instructions that configure the DSP 802 to provide the desired functionality, or the application software may be processed by an interpreter or compiler to indirectly configure the high-level software instructions of the DSP 802.

An antenna and front-end unit 806 may be provided to convert between wireless and electrical signals, enabling the UE 10 to send and receive information from the cellular network or some other available wireless communication network or peer UE 10. In an embodiment, the antenna and front-end unit 806 may include multiple antennas to support beamforming and/or multiple-input multiple-output (MIMO) operation. As known to those skilled in the art, MIMO operation can provide spatial diversity for overcoming difficult channel conditions and/or increasing channel throughput. Antenna and front end unit 806 may include antenna tuning and/or impedance matching components, RF power amplifiers, and/or low noise amplifiers.

The RF transceiver 808 provides frequency offset, converts received RF signals to baseband and converts baseband transmit signals to RF. In some descriptions, a wireless transceiver or RF transceiver may be understood to include other signal processing functions such as modulation/demodulation, encoding/decoding, interleaving/deinterleaving, spreading/despreading, inverse fast Fourier transform (IFFT)/Fast Fourier Transform (FFT), cyclic prefix addition/removal, and other signal processing functions. For clarity, the description here separates the description of this signal processing from the RF and/or radio stages and conceptually distributes this signal processing to the analog baseband processing unit 810 and/or the DSP 802 or other central processing unit. In some embodiments, RF transceiver 808, portions of antenna and front end 806, and analog baseband processing unit 810 may be combined in one or more processing units and/or application specific integrated circuits (ASICs).

Analog baseband processing unit 810 may provide various analog processing of inputs and outputs, such as input from microphone 812 and earphone 816 and output to earpiece 814 and earphone 816 . To this end, the analog baseband processing unit 810 may have ports for connection to a built-in microphone 812 and earpiece 814 so that the UE 10 may be used as a cellular phone. The analog baseband processing unit 810 may also include ports for connecting headphones or other hands-free microphone and speaker configurations. Analog baseband processing unit 810 may provide digital-to-analog conversion in one signal direction and analog-to-digital conversion in the opposite signal direction. In some embodiments, at least some of the functionality of analog baseband processing unit 810 may be provided by digital processing components, such as DSP 802 or other central processing unit.

DSP 802 can perform modulation/demodulation, encoding/decoding, interleaving/deinterleaving, spreading/despreading, inverse fast Fourier transform (IFFT)/fast Fourier transform (FFT), cyclic prefix addition/removal , and other signal processing functions associated with wireless communications. In an embodiment, for example in code division multiple access (CDMA) technology applications, for transmitter functions, DSP 802 can perform modulation, coding, interleaving and spectrum spreading, and for receiver functions, DSP 802 can perform despreading, despreading, Interleave, decode and demodulate. In another embodiment, for example in Orthogonal Frequency Division Multiple Access (OFDMA) technology applications, for transmitter functions, DSP 802 can perform modulation, coding, interleaving, inverse fast Fourier transform, and cyclic prefix addition , for receiver functions, DSP 802 can perform cyclic prefix removal, fast Fourier transform, deinterleaving, decoding, and demodulation. In other wireless technology applications, other signal processing functions, and combinations of signal processing functions, may be performed by the DSP 802.

DSP 802 may communicate with a wireless network via analog baseband processing unit 810. In some embodiments, the communication may provide an Internet connection so that the user may gain access to content on the Internet and may send and receive email or text messages. Input/output interface 818 interconnects DSP 802 with various memories and interfaces. Memory 804 and removable memory card 820 may provide software and data to configure the operation of DSP 802. Among these interfaces may be a USB interface 822 and a short-range wireless communication subsystem 824 . The USB interface 822 can be used to charge the UE 10 and can also enable the UE 10 to exchange information with a personal computer or other computer system as a peripheral device. The short-range wireless communication subsystem 824 may include an infrared port, a Bluetooth interface, a wireless interface compliant with IEEE 802.11, or any other short-range wireless communication subsystem that may enable the UE 10 to communicate wirelessly with other nearby mobile devices and/or wireless base stations to communicate.

The input/output interface 818 may also connect the DSP 802 to an alarm 826 that, when triggered, causes the UE 10 to provide a notification to the user by, for example, ringing, playing a melody, or vibrating. Alert 826 may serve as a mechanism for alerting the user to any of various events such as incoming calls, new text messages, and appointment reminders, either by silent vibration or by playing a specific tune pre-assigned to a specific caller.

Keypad 828 is connected to DSP 802 via interface 818 to provide a mechanism for the user to make selections, enter information, and otherwise provide input to UE 10. Keyboard 828 may be a full or reduced alphanumeric keyboard (such as QWERTY, Dvorak, AZERTY, and sequential types) or a traditional numeric keypad with letters associated with a telephone keypad. Input keys may include a scroll wheel, an escape or leave key, a trackball, and other navigation or function keys that may be pressed inward to provide other input functions. Another input mechanism may be the LCD 830, which may include touch screen capability and also display text and/or graphics to the user. LCD controller 832 connects DSP 802 to LCD 830.

CCD camera 834 (if equipped) enables UE 10 to take digital pictures. DSP 802 communicates with CCD camera 834 via camera controller 836 . In another embodiment, cameras operating according to technologies other than charge-coupled device cameras may be used. The GPS sensor 838 is connected to the DSP 802 to decode the Global Positioning System signals, thereby enabling the UE 10 to determine its location. Various other peripherals may also be included to provide additional functionality, such as radio and television reception.

FIG. 10 shows a software environment 902 that may be implemented by DSP 802. DSP 802 executes and provides the operating system driver 904 of the platform on which the rest of the software can run. The operating system driver 904 provides drivers for UE hardware and has a standardized interface that can be accessed by application software. The operating system driver 904 includes an application management service ("AMS") 906 that transfers control between applications running on the UE 10. Also shown in FIG. 16 is a web browser application 908 , a media player application 910 and a Java application 912 . Web browser application 908 configures UE 10 to operate as a web browser, allowing users to enter information into forms and select links to retrieve and view web pages. The media player application 910 configures the UE 10 to retrieve and play audio or audiovisual media. The Java application 912 configures the UE 10 to provide games, tools, and other functions. Component 914 may provide the functionality described herein.

The above-mentioned UE 10, base station 120 and other components may include processing components capable of executing instructions related to the above-mentioned actions. FIG. 17 illustrates an example of a system 1000 that includes a processing component 1010 suitable for implementing one or more embodiments disclosed herein. In addition to processor 1010, which may be referred to as a central processing unit (CPU or DSP), system 1000 may include network connectivity devices 1020, random access memory (RAM) 1030, read only memory (ROM) 1040, secondary storage 1050, and input/output (I/O) devices 1060. In some cases, some of these components may be absent, or they may be combined in various combinations with each other or with other components not shown in the figures. These components may be located in a single physical entity, or in more than one physical entity. Any action described herein as taken by the processor 1010 may be taken by the processor 1010 alone or by the processor 1010 in conjunction with one or more components shown or not shown in the figure.

Processor 1010 executes instructions, codes, computer programs or scripts that it can access from network connection device 1020, RAM 1030, ROM 1040 or secondary storage 1050 (which may include various disk-based systems such as hard disk, floppy disk or optical disk). Although only one processor 1010 is shown, multiple processors may be present. Thus, although instructions may be discussed as being executed by a processor, instructions may be executed concurrently, serially, or otherwise by one or more processors. Processor 1010 may be implemented as one or more CPU chips.

Network connectivity device 1020 may take the form of a modem, modem group, Ethernet device, universal serial bus (USB) interface device, serial interface, token ring device, fiber distributed data interface (FDDI) device, wireless local area network ( WLAN) equipment, radio frequency transceiver equipment, such as Code Division Multiple Access (CDMA) equipment, Global System for Mobile Communications (GSM) wireless transceiver equipment, Worldwide Interoperability for Microwave Access (WiMAX) equipment, and/or other well-known devices used to connect to the network. These network connectivity devices 1020 may enable the processor 1010 to communicate with the Internet or one or more telecommunications networks or other networks from which the processor 1010 may receive information or from which the processor 1010 may output information.

The network connectivity device 1020 may also include one or more transceiver components 1025 capable of wirelessly transmitting and/or receiving data in the form of electromagnetic waves, such as radio frequency or microwave frequency signals. Alternatively, the data may propagate in or on an electrical conductor, in a coaxial cable, in a waveguide, in an optical medium such as an optical fiber, or in other media. The transceiver assembly 1025 may include separate receive and transmit units, or a single transceiver. Information sent or received by transceiver component 1025 may include data that has been processed by processor 1010 , or instructions to be executed by processor 1010 . Such information may be received from and output to the network in the form of, for example, computer data baseband signals or signals embodied in carrier waves. Data may be ordered according to different orders required for processing or generating data or transmitting or receiving data. A baseband signal, a signal embedded in a carrier wave, or other types of signals now in use or later developed can be referred to as a transmission medium and can be generated according to several methods well known to those skilled in the art.

RAM 1030 may be used to store volatile data and possibly instructions for execution by processor 1010. ROM 1040 is a non-volatile memory device that typically has a smaller memory capacity than that of secondary storage 1050. ROM 1040 may be used to store instructions as well as store data that may be read during execution of the instructions. Accesses to RAM 1030 and ROM 1040 are generally faster than accesses to secondary storage 1050. Secondary storage 1050 typically includes one or more disk drives or tape drives and can be used for non-volatile storage of data, or for overflow data if RAM 1030 is not large enough to hold all working data storage device. Secondary storage 1050 may be used to store programs that are loaded into RAM 1030 when programs are selected for execution.

I/O devices 1060 may include liquid crystal displays (LCDs), touch screen displays, keyboards, keypads, switches, dial pads, mice, trackballs, voice recognizers, card readers, paper tape readers, printers, video monitors , or other well-known input/output devices. Likewise, transceiver 1025 may be considered a component of I/O device 1060 instead of or in addition to being a component of network connectivity device 1020 . Some or all of I/O device 1060 may be substantially similar to various components shown in the aforementioned figures of UE 10, such as display 702 and input 704.

Although several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods may be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. This example should be considered illustrative rather than restrictive, and no limitation to the details given herein is intended. For example, various units or components may be combined or integrated into another system, or specific features may be omitted or not implemented.

Furthermore, techniques, systems, subsystems, and methods described and illustrated in various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure . Other items shown or described as being connected or directly connected or communicating with each other may be indirectly connected or communicating with each other through some interface, device, or intermediate component, whether electronic, mechanical, or otherwise. Changes, substitutions and other examples of alterations can be ascertained by those skilled in the art and can be made without departing from the spirit and scope disclosed herein.

To apprise the public of the scope of the invention, the following claims are presented.

Claims (10)

1. A method of communicating using a wireless communication network, comprising: receiving a channel quality indicator (CQI) from a first UE, the first UE being served by a base station, the CQI characterizing a channel between the first UE and the base station when the base station transmits at high power quality; determining a first modulation and coding scheme (MCS) when the base station transmits at low power based on the CQI; and communicating with the first UE using low power transmission when the spectral efficiency of the first MCS is equal to or higher than the spectral efficiency of a predetermined MCS. 2. The method according to claim 1, comprising: when the spectral efficiency of the first MCS is equal to or higher than the spectral efficiency of a predetermined MCS: allocating a first set of resources in a first resource block (RB) to the first UE; and Allocating the first resource set in the first RB to a second UE, the second UE being served by a relay node (RN), the RN communicating with the base station. 3. The method of claim 2, comprising sending the first UE the First RB. 4. The method of claim 1 , comprising: sending a Physical Downlink Control Channel (PDCCH) Downlink Control Information (DCI) message to the first UE, the PDCCH DCI message identifying a message from the base station to A power spectral density (PSD) level of the first UE's transmission. 5. The method of claim 1, comprising characterizing the first UE as a cell edge UE when the spectral efficiency of the first MCS is lower than the spectral efficiency of the predetermined MCS. 6. The method according to claim 5, comprising: when the spectral efficiency of the first MCS is lower than the spectral efficiency of the predetermined MCS: allocating a first set of resources in a first set of RBs to the first UE; and Allocating a second set of resources in the first set of RBs to a second UE, the second set of resources being different from the first set of resources, the second UE being served by a relay node (RN), the The RN communicates with the base station. 7. The method of claim 1, wherein determining the first MCS comprises: using the CQI to determine a signal-to-interference and noise ratio (SINR); and The SINR is used to determine the first modulation coding scheme MCS. 8. A device for communicating using a wireless communication network, comprising: Means for receiving a channel quality indicator (CQI) from a first UE, the first UE being served by a base station, the CQI characterizing the communication between the first UE and the base station when the base station transmits at high power channel quality between means for determining a first modulation coding scheme (MCS) when the base station transmits at low power based on the received CQI; and means for communicating with the first UE using low power transmission when the spectral efficiency of the first MCS is equal to or higher than the spectral efficiency of a predetermined MCS. 9. The apparatus according to claim 8, comprising: means for performing the following operations when the spectral efficiency of the first MCS is equal to or higher than the spectral efficiency of a predetermined MCS: allocating a first set of resources in a first resource block RB to the first UE; and Allocating the first set of resources in the first RB to a first UE, the second UE is served by a relay node (RN), and the RN communicates with the base station. 10. The apparatus according to claim 8, comprising: when the spectral efficiency of the first MCS is equal to or higher than the spectral efficiency of a predetermined MCS, transmitting to the first UE using a low power spectral density (PSD) means of the first RB.